(1) Field of the Invention
Thermosetting resin decorative plates such as melamine resin decorative plates and diallyl phthalate resin decorative plates are widely used for furniture, desks, tables and interiors in houses and buildings.
The present invention relates to a method for the preparation of a thermosetting resin decorative material which has a pattern with varied gloss thereon and which is capable of heightening the surface design effect of thermosetting resin decorative plates mentioned above, and the present invention also relates to a transfer sheet which is used in the above-mentioned method.
(2) Description of the Prior Art
As thermosetting resin decorative plates having patterns with varied gloss thereon, there are known decorative plates having woodgrain patterns where recesses are provided as conduits, and embossed decorative plates having geometrical patters.
Examples of the method for the preparation of the thermosetting resin decorative plates having patterns with varied gloss thereon include (1) a method which comprises superposing a mirror plate having a rough portion formed by etching or the like upon a resin-impregnated paper, then pressing the resulting laminate at an elevated temperature, and after the resin in the resin-impregnated paper has been set, removing the mirror plate therefrom; (2) a method in which the mirror plate used in the above-mentioned method (1) is replaced with a resin plate having the rough portion; (3) a method in which the mirror plate used in the above-mentioned method (1) is replaced with an embossed film which has been formed by embossing a thermoplastic resin film by the use of an engraved roller; and (4) a method which comprises printing a pattern paper with an ink or a foamed ink for inhibiting the curing of a resin, then allowing the resin to penetrate the pattern paper, and thermally pressing the resulting resin-impregnated paper by the use of a heated mirror plate so as to weaken the ink-printed portions alone of the resin.
However, in the case that such a mirror plate or resin plate is used, it is necessary to previously prepare many plates having various patterns. In consequence, the manufacturing cost of the mirror plates and resin plates is burdensome, and a time of exchanging a plate having one pattern for another one having a different pattern is necessary during manufacturing. For these reasons, the above-mentioned methods are scarcely suitable for the manufacture of various kinds of products. In addition, the resin plate has no release characteristics to the resin (thermosetting resin) in the resin-impregnated paper, and thus it is necessary to interpose a release sheet or a metallic foil having release characteristics between the resin plate and the resin-impregnated paper, with the result that the gloss based on fine rough patterns cannot be reproduced, though coarse rough patterns are reproducible.
In the above-mentioned method of making use of the embossed film, the embossed pattern on the film is liable to vanish owing to heat and pressure when pressed, so that the film comes to flatten, because the embossed film is thermoplastic. Therefore, also in this method, the reproduction of the gloss based on the rough pattern is insufficient.
In the method of employing the ink or the foamed ink for inhibiting the curing of the resin, it is hard to control shapes of portions which are different in glossy state, i.e., glossy and unglossy portions. In addition, the weakened portions of the resin are physically poor. In this method, moreover, the resin in the weakened portions adheres to the mirror plate when pressed, and thus the adhered resin must be removed therefrom each time manufacturing is made, or alternatively a release sheet is interposed between the mirror plate and the resin-impregnated paper so as to prevent the resin in the weakened portions from adhering to the mirror plate.
On the contrary, Japanese Patent Laid-open Publication No. 21210/1972 discloses a method (5) for reproducing a glossy state of a base sheet on a support which comprises first printing an ink on a film having a cotrolled glossy state to form a base sheet partially having glossy portions, then forming a transfer layer on the base sheet to obtain a transfer sheet, allowing the latter to adhere to the support, and removing the base sheet alone therefrom.
However, as described in examples of this Japanese publication, a synthetic rubber or a thermoplastic resin is stuck on the surface of the support in the case that the transfer layer contactually formed on the base sheet is composed of the synthetic rubber or the thermoplastic resin, though the base sheet can be smoothly released from the transfer layer. As a result, the support on which the synthetic rubber or the thermoplastic resin is stuck is remarkably poor in physical properties such as hardness and scuffing resistance. In addition, when the transfer layer is composed of the thermoplastic resin, the ink cannot be released successfully from the transfer layer, so that the ink tends to be left on the support.
Furthermore, also in the case that the base sheet alone used in the method (5) is superposed upon a resin-impregnated paper and the resulting laminate is then heated and pressed, the ink is hardly released from the resin-impregnated paper, so that the ink remains on the resin-impregnated paper.
Therefore, an object of the present invention is to provide a transfer sheet for transferring a glossy state in which glossy and unglossy portions can be smoothly released from a resin-impregnated paper, and a method for the preparation of a decorative material having locally different glossy states with high production efficiency and with high accuracy, the method being additionally suitable for the manufacture of many kinds of products.